Custom Logo and Colors

I managed to change the fonts and it works like a dream. I would like to know two things:

1. I have a logo that is just amazing. However, i need it to fit into the buddypress theme properly. I added it but the size is so small that it looks terrible. Is there anyway to change the properties of the buddypress theme(member and home) to allow me to add a bigger logo(height and width)

2. Adjusting the colors of the theme. Whats the best way to do this? I tried editing the image files but doesn’t work too great.Is there a better way?